Gas‐Phase Reaction Study of Disilane Pyrolysis: Applications to Low Pressure Chemical Vapor Deposition

Abstract

The gas-phase thermal reactions during disilane decomposition at low pressure chemical v por deposition conditions were studied from 300 to 1000 K using resonance enhanced multiphoton ionization (REMPI) and multiphoton ionization (MPI). REMPI of gas-phase St, mass 28, was detected from 640 to 840 K and 1 to 10 Torr, with a maximum signal intensity between 700 to 720 K. During disilane decomposition, o Sil l (427.8 nm), Sill2 (494-515 nm), or Sill3 (419.0 nm) was detected. MPI of higher silanes, silenes, and silylenes were detected through mass fragments 2, 32, and 60; these species reached a maximum signal intensity 20 degrees prior to the mass-28 maximum. Modeling studies that included a detailed low pressure gas-phase kinetic scheme predict relative gas-phase partial pressures generated during disilane pyrolysis. The model predicted experimental trends in the Si partial pressure and the higher silane, silene, and silylene partial pressures. Disilane (SigH6) has been considered as a replacement for silane (SiH~) in specific silicon low pressure chemical vapor deposition (LPCVD) applications. Polycrystalline silicon (poly-Si) has applications in thin film transistors (TFT) for active matrix liquid crystal displays, image sensors, and high value load resistors in static memory circuits. Large